diff --git a/ChangeLog b/ChangeLog
index 98613cb60f..54b8246dd4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sun Jan 23 11:39:18 2011  Tanaka Akira  <akr@fsij.org>
+
+	* vm_exec.h: parenthesize macro arguments.
+
 Sun Jan 23 10:33:02 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* template/fake.rb.in (ruby): suppress warnings.
diff --git a/vm_exec.h b/vm_exec.h
index 7208c3d6e5..caf752a76b 100644
--- a/vm_exec.h
+++ b/vm_exec.h
@@ -20,8 +20,8 @@ typedef rb_iseq_t *ISEQ;
 
 #ifdef  COLLECT_USAGE_ANALYSIS
 #define USAGE_ANALYSIS_INSN(insn)           vm_analysis_insn(insn)
-#define USAGE_ANALYSIS_OPERAND(insn, n, op) vm_analysis_operand(insn, n, (VALUE)op)
-#define USAGE_ANALYSIS_REGISTER(reg, s)     vm_analysis_register(reg, s)
+#define USAGE_ANALYSIS_OPERAND(insn, n, op) vm_analysis_operand((insn), (n), (VALUE)(op))
+#define USAGE_ANALYSIS_REGISTER(reg, s)     vm_analysis_register((reg), (s))
 #else
 #define USAGE_ANALYSIS_INSN(insn)		/* none */
 #define USAGE_ANALYSIS_OPERAND(insn, n, op)	/* none */